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A new strategy is described for lectin-selective labeling based on an acyl transfer reaction directed by ligand-tethered 4-dimethylaminopyridine (DMAP). This new labeling method is applicable for purified lectin in test tubes and also for crude mixtures such as Escherichia coli lysates or homogenized animal tissue samples expressing Congerin.

Pyridylamination is a versatile method for fluorescence labeling of oligosaccharides. The technique affords sensitive detection of saccharides with reducing termini and high-resolution separation by high-performance liquid chromatography. The conventional method, based on a liquid-phase reaction, has been extensively used in various aspects of glycobiology and glycotechnology. Unfortunately, the necessity for removing excess 2-aminopyri-dine makes the technique both laborious and time-consuming. Furthermore, removal of excess reagent can result in a significant loss of short saccharide components. In the present paper, we report an alternative methodology based on a 'gas-phase' reaction, in which dried saccharides are reacted with vaporized 2-aminopyridine. The resultant Schiff base was also reduced in the gas phase within the same reaction microtube using a purpose-built device. The newly developed procedure was applied to both monosaccharide (GlcNAc) and oligosaccharides (isomalto-oligosaccharides) at quantitative yields with no requirement to remove excess reagent. The acid-labilesialyl linkages of ([alpha]-2-6-disialobiantennary oligosaccharides proved to be fully stable during the procedure. The developed method was also successfully applied to profiling N-linked oligosaccharides liberated from glycoproteins by hydrazinolysis and, thus, should contribute to various fields of glycomics.

Incorporation of aminomethylene substituents in highly substitute and functionalized 2-pyridones was accomplished by using microwave-assisted organic synthesis (MAOS). This resulted in highly substituted 2-pyridones with 48-93% yields.

It has been possible to use (2+1) resonance-enhanced multiphoton ionization spectroscopy in the gas phase to measure the enthalphy difference between axial and equatorial 3-methyltetrahydropyrans.

Research was conducted to examine the reactions of 6-aminopyrimidines with biselectrophiles. The objective is to investigate the possible role of steric hindrance imposed by a phenyl substitution on the alpha-halo ketone on the direction of ring closure by performing the cyclocondensation of 2,4,6-triaminopyrimidine and 2-bromo-4-phenylcyclohexanone. Results indicate the importance of the electron density at the C5-carbon.

Research was conducted to examine the refractive indices of the optically nonlinear organic crystal (S)-3-methyl-5-nitro-N-(1-phenylethyl)-2-pyridinamine. The refractive indices were measured from 480 to 660 nm and fitted to four-parameter Sellmeier equations with an accuracy of +/-3 x 1/10 to the 3rd power to +/-5 x 1/10 to the 3rd power. The values of the n(sub x), n(sub y) and n(sub z) refractive indices at 532 nm were found from the Sellmeier equations to be 1.690, 1.901 and 1.725, respectively.

Quinidine was employed as an open channel probe in the examination of the kinetic state of 4-aminopyridine blocked channels. Quinidine, in the presence of 0.2-1 mM of 4-aminopyridine, was found to stem charge return and promote partial charge immobilization. Results suggest that the 4-aminopyridine resident in the channel provided an allosteric modulation of the quinidine binding site.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), has been used for structure characterization of 1-aminopyrene-3,6,8-trisulfonate (APTS)-derivatized oligosaccharides previously separated by capillary electrophoresis (CE). The resolved components were first isolated by employing an automated high-resolution fraction collector. Using on-probe sample cleanup with a cation-exchange resin and a matrix mixture of (1:1) 6-hydroxypicolinic acid and 3-hydroxypicolinic acid, APTS-labeled oligosaccharides were successfully detected by MALDI-TOF MS in the negative ionization mode. Each APTS-labeled oligosaccharide produced single [[M - H].sup.-1] peaks. Detection limits for standard APTS-derivatized oligosaccharide (maltoheptaose) were down to 30 fmol. APTS labeled maltooligosaccharides and various standard carbohydrates were separated and collected by CE, followed by molecular weight determination with MALDI-TOF MS. The mass spectral characterization enhances the power of the CE analysis of oligosaccharides.

The (S)-ethyl beta-amino-3-pyridinepropanoate (3) is synthesized from enantiopure sulfinimines. The sulfinamide 7F is obtained from the addition of lithium enolate of ethyl acetate to (R)-(-)-N-(3-pyridylmethylidene)-beta-methoxynaphthalenesulfinimide. The main isomer (Rs,3S)-7b, after flash chromatography, is separated to the diastereomerically pure 7b. 7b yields (S)-(+)-ethyl beta-amino-3-pyridinepropanoate as its bistrifluoroacetic following hydrolization by trifluoroacetic acid and subsequent flash chromatography.

Tricyclic aminopyridines can be prepared using cadmium promoted cyclization. A study finds that cyclocondensation of o-amino nitriles with cyclic 1,3-diones can function as a synthetic route to collect fused tricyclic aminopyridine sources. The process begins with the development of an enaminone that is cyclized at 120 degrees centigrade to 190 degrees centigrade in the presence of Lewis acids.

4H-thiopyran-4-one 1,1dioxides is synthesized by the use of sodium hydrosulfide hydrate instead of hydrogen sulfide gas. The use of sodium hydrosulfide hydrate provides large quantities of the thiopyran dioxides. The process of synthesis involves the double dehydrogenation of the saturated sulfones by using hetroaryl or aryl substituents.

Condensation of malonitrile having corresponding 4H-1,1-dioxothiopyran-4-one results in the formation of a variety of 4H-1,1-dioxo-4-(dicyanomethylidience)thiopyrans. The thiopyrans thus produced are capable of functioning as electron-transport materials. The x-ray crystal structure of the thiopyrans reveal that these complexes are made of a planar ring which is boat shaped in the tert-butyl-substituted derivatives.

2,3-diaminopyridines offer a route for efficient regioselective synthesis of N-alkylated 2,3-diaminopyridines with substituents at 2 and 3 positions and imidazo (4,5-b) pyridines, which are cyclized products resulting from the reactivity of amino groups at the 2 and 3 positions. The nature of reaction conditions induce the formation of N-1 or N-3-alkylated imidazopyridines from the intermediate 2-formamido-3-aminopyridine.

The injection of pyranine(8-hydroxypyrene-1,3,6-trisulfonate), an excited-state proton emitter, into the aqueous space of submitochondrial particles produces dye which recorded acidification in the space. The respiratory processes and the reverse electron transfer of the vesicles are not influenced by the dye concentration. The protons are photodissociated from the 8-hydroxy position by the dye by pulse irradiation.

A new and practical way to prepare 6-substituted 2-(N-acetylaamino)pyridines involvescyclizing 5-oximinoalkanenitriles with acylchloride/acetic anhydride (or Ac2O/HCl). Except for the oximes of 5-oxopentanenitriles which yield glutaronitriles instead, all the oximes eventually form, after alkaline hydrolysis, 2-aminopyridines in 40-65% yields. Their reaction mechanism involves formation of an alpha-acetoxy imine that eliminates acetic acid and isomerizes to a conjugated amininitrile, which cyclizes to the aminopyridine.

A first-generation approach to the stereocontrolled introduction of substituents syn or anti relative to an eta5-CpMo(CO)2 unit coordinated to a lateral pi-ligand was described and is applied to a pyranone ring. The pyranone carbonyl group was replaced by two different substituents, R1 and R2, and it is observed that the order of introduction of substituents R1 and R2 relative to the molybdenum unit affects the stereochemistry of the substituents.

The preparation of bipyridylalanine, bipyridyl-functionalized peptide derivatives and copper complexes of some peptide-bipyridyls were reported. The methods used to introduce the bipyridyl ligand into a peptide were direct insertion of the bipyridine group onto a site of the peptide and synthesis of a new amino acid containing the group to for use in the peptide preparation. The compounds were characterized by electrospray ionization mass spectrometry.

Diacid hosts with closed resting states bind less to water in chloroform than those with open binding sites. The intramolecular hydrogen bonds in the less reactive diacids are considerably stronger than in the easily hydrated diacids. The behavior of the closed diacid hosts makes them resistant to hydration attacks and facilitates binding through an induced-fit mechanism. Also, these closed diacid hosts exhibit less sensitivity to environmental changes regardless of the effects of similar changes on the enthalpy and entropy of open diacid hosts.

The highly efficient and enantioselective Ru-catalyzed AROM/CM reactions leading to synthesis of functionalized tetrahydropyrans have been described. Optically enriched pyrans can be functionalized with excellent regioselectivity in a variety of ways.

The structural parameters obtained through single-crystal X-ray diffraction analysis of the one-dimensional H-bounding motif expressed by 3,6-diaminopyridazine are applied to the design of related monomeric, dimeric, and trimeric duplex molecular strands. The results provide further insight into the structural and interactional features of synthetic duplex oligomers required for high-affinity and high-specificity binding.

Resonant-enhanced multiphoton ionization (REMPI) and mass-analyzed threshold ionization (MATI) spectra of 2-aminopyridine (2AP-NH2).Arn clusters are presented to give the S1-S0 spectral origins of 33 439 and 33 411 cm to the power -1 for the 2AP-NH2.Ar and 2AP-NH2.Ar2 clusters, respectively, and also their respective adiabatics ionization energies of 8.0881+_0.0021 and 8.0676 +_ 0.0020 eV. Ab initio calculated cluster structures are also provided.

The organic crystal (S)-3-methyl-5-nitro-N-(1-phenylethyl)-2-pyridinamine that were previously identified by the powder technique as a promising nonlinear optical material, the large single crystals (3 * 3 * 2 cm(super 3)) of which is grown by temperature lowering of a seeded supersaturated solution in acetone is reported. Refined refractive indices are obtained from the predicted angles of incidence of the phase-matched second harmonic signals.

DuBell, W. H., W. J. Lederer, and T. B. Rogers. [K.sup.+] currents responsible for repolarization in mouse ventricle and their modulation by FK-506 and rapamycin. Am. J. Physiol. Heart Circ. Physiol. 278: H886-H897, 2000.--Modulation of mouse ventricular action potentials and [K.sup.+] currents was examined using the whole cell patch-clamp technique. The composite mouse ventricular [K.sup.+] current (consisted of an outward transient followed by a slowly decaying sustained component. Use of the [K.sup.+] channel blockers tetraethylammonium and 4-aminopyridine and a transgenic mouse model revealed three pharmacologically and kinetically distinct currents: [I.sub.to], which contributed to the transient component; [I.sub.K], which contributed to the sustained component; and a slowly activating current ([I.sub.slow]), which contributed to both components. The immunosuppressant FK-506 increased action potential duration at 90% repolarization by 66.7% by decreasing the sustained component (-48% at + 60 mV) and prolonging recovery from inactivation (by 26% at 200 ms) of the transient component. These effects were isolated to [I.sub.K] and [I.sub.to], respectively. Rapamycin had strikingly similar effects on these currents. Both FK-506 and rapamycin are known to target the immunophilin FKBP12. Thus we conclude that FKBP12 modulates specific mouse [K.sup.+] channels, and thus the mouse ventricular action potential, by interacting directly with [K.sup.+] channel proteins or with other associated regulatory proteins. transient outward current; FK-binding proteins; Kv1.5

Research was conducted to prove that protected alpha-amino acids is generated by the catalysis of the deracemization/ring opening of azlactones by chiral 4-(dimethylamino)pyridines (DMAP). The study provides a new method for nonenzymatic enantioselective catalysis of the process. It also suggests that planar-chiral DMAP derivatives may be effective as enantioselective catalysts for a substantial subset of the reactions known to be catalyzed by DMAP.

A new approach for the development of aminopyridines is discussed. This method involves palladium-catalyzed cross-coupling of aryl bromides and primary amines containing chelating bis-(phosphine) ligands under mild conditions. Unlike reactions which occur in the presence of sodium tert-butoxide, the use of palladium catalyst results in the formation of the product in excellent yield.

Anodic oxidation of olefinic alpha-stannyl ethers and carbamates leadsto intramolecular formation of C-C bonds. In dichloromethane and with tetrabutylammoniumborotetrafluoride (Bu4NBF4) as electrolyte, the ethers undergo endo cyclization via a carbocation intermediate to form the corresponding pyrans and seven-membered oxo-rings. Carbamates, on the other hand, yield piperidines. A unique feature of these cyclizations is the nucleophilic addition of the fluoride ion (from Bu4NBF4) to one of the olefiniccarbons. The process then provides an added synthetic route to fluoro compounds.